<template>
  <div class="big-img">

    <img ref="img1" src="../image/放大镜.webp" />
    <div class="event" @mousemove="move"></div>
    <div class="big-right">
      <img ref="img2" src="../image/放大镜.webp" :style="{left:-2*left+'px',top:-2*top+'px'}" />
    </div>
    <div class="mask" ref="mask" :style="{left:left+'px',top:top+'px'}"></div>
  </div>
</template>

<script>
import _ from 'lodash'
export default {
  name: 'Zoom',
  data() {
    return {
      top: 0,
      left: 0
    }
  },
  methods: {
    move: _.throttle(function (e) {
      let x = e.offsetX - this.$refs.mask.clientWidth / 2
      if (x < 0) x = 0
      if (x > 214) x = 214
      let y = e.offsetY - 107
      if (y < 0) y = 0
      if (y > 214) y = 214
      this.left = x
      this.top = y
    }, 1000 / 60)
  }
}
</script>

<style lang="less" scoped>
.big-img {
  width: 428px;
  height: 428px;
  border: 1px solid #eee;
  position: relative;
  z-index: 1000;

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1009;
  }

  img {
    width: 100%;
    height: 100%;
  }

  // 挡板，挡板和图片大小成比例关系1:2
  .mask {
    width: 50%;
    height: 50%;
    border: 1px solid transparent;
    background-color: pink;
    opacity: 0.4;
    position: absolute;
    left: 0;
    top: 0;
    z-index: 1005;
    cursor: pointer;
    display: none;
  }

  // 放大图，框大小和里面的图成比例1:2
  .big-right {
    width: 100%;
    height: 100%;
    border: 1px solid lightblue;
    position: absolute;
    left: 102%;
    top: -1px;
    z-index: 1005;
    overflow: hidden;
    display: none;

    img {
      width: 200%;
      height: 200%;
      position: absolute;
      top: 0;
      left: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big-right {
    display: block;
  }
}
</style>


<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>